1. Field of the Invention
The present invention relates in general to a small watercraft, and in particular to a cooling system for a small watercraft.
2. Description of Related Art
Personal watercrafts have become popular in recent years. Jet propulsion units usually power such watercrafts and offer a number of advantages over propeller driven systems. One such advantage is the ability to run in very shallow water. The jet propulsion units can also supply pressurized cooling water to an open-loop cooling system for the engine and the associated exhaust system.
For this purpose, watercraft today commonly include a delivery conduit which extends between the jet propulsion unit and a water jacket of the engine. The delivery conduit is connected to a water influent port which normally communicates with the pressure chamber of the propulsion device. Pressurized water within the chamber flows into the influent port and into the delivery conduit. The cooling water thence flows through the engine and exhaust system water jackets, and is discharged overboard, usually through a telltale port and/or the exhaust system.
Although the jet propulsion unit provides an adequate source of pressurized water, such water is not always free from foreign debris. Frequently foreign objects and particles may be drawn into the jet propulsion unit, especially when the jet propulsion unit operates in shallow water. Such foreign and small articles and objects often include such matter as weeds, small pebbles and stones, small pieces of driftwood and like debris. If the jet propulsion unit draws in such articles and the articles become entrained in the water flow through the jet propulsion unit, the foreign articles often enter the delivery conduit and clog, either partially or entirely, the water flow through the cooling system. As a result, an adequate supply of cooling water may not be delivered to the engine and the associated components, such as for example, the exhaust system. Overheating of the engine and exhaust system thus can result. Operating the engine and exhaust system at elevated temperatures can of course significantly reduce the performance of the engine, and under some conditions can possibly damage the engine.
Some personal watercraft have employed a filter within the delivery conduit to remove foreign material. The foreign material which enters and is present in the delivery conduit upstream of the filter, however, can still clog the delivery conduit as well as the filter itself. Such an in-line filter therefore requires routine maintenance and periodic replacement, which adds to the expense and effort associated with running the watercraft. In addition, the inclusion of an in-line water filter and the associated filter housing and fittings, increases the cost of the watercraft.